Shaving head for dry shavers having a coated outer surface

ABSTRACT

1,134,883. Dry shavers. GILLETTE CO. 24 Nov., 1965 [24 Nov., 1964], No. 49996/65. Heading B4B. [Also in Division C7] A shearing foil for a dry shaver comprises a perforated base sheet 3&lt;SP&gt;1&lt;/SP&gt; electrolytically coated with harder material 4&lt;SP&gt;1&lt;/SP&gt; which provides sharp cutting edges 5&lt;SP&gt;1&lt;/SP&gt; but leaves uncoated that side of the base sheet which will face a blade of the shaver. Fig. 1 (not shown) illustrates making a foil base sheet (3) by electrolytically depositing resilient material, e.g. Ni, on to a metal die (1) having an insulating layer (2) with a configuration corresponding with that of the holes to be produced in the foil. A layer of harder material (4), e.g. of Cr, Rh or hard Ni, is electrolytically deposited on the base sheet (3) while still on the die. Prior to this deposition of harder material, portions of the base sheet may be masked with varnish. The base sheet (3) and harder material (4) may both be electrolytically deposited from a bath of the same composition but using different current densities. During use the shaver cutter causes the foil to wear, the less hard material wearing more than the harder material as illustrated in Fig. 3 (not shown).

Nov. 12, 1968 B. FUTTERER- 3,409,934.

I SHAVING HEAD FOR DRY SHAVERS HAVING A COATED OUTER SURFACE Filed Dec.17, 1965 m W//////////////////fi7771\3 i////////////; 3 H6. 3

BODO FUTI'TERER" INVENTOR.

Attbmey United States Patent 3,409,984 SHAVING HEAD FOR DRY SHAVERSHAVING A COATED OUTER SURFACE Bodo Fiitterer, Sarnen, Switzerland,assignor to The Gillette Company, Boston, Mass., a corporation ofDelaware Filed Dec. 17, 1965, Ser. No. 524,661 6 Claims. (Cl. 30346.51)

ABSTRACT OF THE DISCLOSURE A shearing foil having a substrate body withperforations conforming to the tooth formation of a cooperating blade,and a relatively thin coating of a material harder than said substratebody on the outer surface of the body and extending along the peripheryof the perforations to the inner surface of the body while leaving theinner surface devoid of a coating and completely exposed to thereby formhard cutting edges along the rims of the perforations at their innersurface.

My present invention relates to shearing foils, i.e. to contoured and/orapertured protective foils as used in cooperation with one or moreunderlying blades whose teeth are separated by spaces registering withthe perforations of the foil.

Shearing foils are employed in many types of dry shavers. The thinnersuch foils can be made, the closer are the shaves they afford.

In the production of thin, hard foils, capable of assuming an unlimitedvariety of hole patterns, galvano-plastic manufacturing processes havecome increasingly into use in lieu of prior methods employing stampedand hardened sheet steel. However, a galvanically produced depositinherently combines a high degree of hardness with marked brittlenessand consequently its hardness has to be reduced in order to minimize anyrisk of fracture. Moreover, conventionally electroformed shearing foilsdo not retain their sharp edges as long as do steel foils.

Accordingly, it is an important object of this invention to provide animproved shearing foil combining a high degree of hardness along itscutting edges with good elasticity, so as to be substantiallyfracture-proof, as well as a relatively simple process for making suchfoils.

Another object of my invention is to provide a shearing foil of thisdescription whose edges are practically self-sharpening.

These objects are realized, in accordance with my invention, byproviding on one surface of a supporting metal foil, having a chosenarray of gaps or perforations, a coating of greater hardness whichextends into the perforations and covers the peripheral walls thereof.The other surface of the foil, i.e. the one which is to contact theblade upon assembly in a shaver, is not coated with the hard material.Such shearing foils exhibit abrasionresistant cutting edges along therims of the perforations where the hard coating meets the exposedsurface of the softer substrate. In use, this substrate is eroded fasterthan the coating so as to form an acute rake angle along each cuttingedge. As a further result of this erosion, the friction between theshearing foil and the cutter blade is greatly reduced. Consequently,upon continued use there will occur but little further wear on the foilsurface contacting the blade, with consequent preservation of th shapeof the hard cutting edges.

According to another aspect of my invention, a shearing foil of thecharacter described is produced by depositing a relatively soft layer ofmetal on a conductive matrix having a chosen array ofperforation-defining portions masked with an insulating substance toprevent a deposi "ice tion of the metal thereon. A coating of arelatively hard material is then applied to the exposed surface of theelectroformed layer, either electrolytically or by some other method ofdeposition, so as to extend to the very botto mof the peripheral wallsof the perforations which are formed in the supporting layer at thelocations of the nonoconductive zones.

For a better understanding of the invention, reference is had to thefollowing description taken in conjunction with the accompanying drawingin which:

FIG. 1 is a plan view of part of a shaving-head assembly including ashearing foil embodying the invention;

FIG. 2 is a cross-sectional view of an arrangement for making theshearing foil of FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the freshly madeshearing foil; and

FIG. 4 is a view similar to FIG. 3, showing the foil after an initialperiod of use.

FIG. 1 shows part of a shaving head 10, as used in conventional electricshavers, wherein a set of laterally oscillatable blades 11, 12 areoverlain by a protective foil 13 whose slot-like perforations 14register with the interteeth gaps 15 of the blades.

In FIG. 2 there is shown a conductive matrix or die 1 with surfacerecesses occupied by an insulating layer 2, the distribution ofinsulation 2 corresponding to the pattern of perforations 14 in FIG. 1.Upon die 1 there is galvanically deposited a layer 3 of a metal,preferably nickel, which for reasons of elasticity should have arelatively low hardness of, say, 400 Vickers. Because of thethree-dimensional growth of the galvanic deposit, the voids formedtherein are somewhat narrower than the corresponding recesses in matrix1 so that the electroformed body 3 extends partly, with a convexcurvature, over insulating layer 2. A thin, hard coating 4 is thendeposited on layer 3 to define a sharp edge 5 at the bottom of eachperforation 14. Layers 3 and 4, differing in hardness, may be bothcathodically formed either from the same or from different metals. Whereboth layers are made from the same metal, the harder layer 4 may beproduced by varying the conditions of electrodeposition, e.g. byincreasing the current density.

Thus, covering layer 4 may consist of a metal such as chromium, rhodium,or hard nickel. This coating may also be produced from non-metallicmaterials such as ceramic or vitreous substances, and particularly inthis instance may be deposited on substrate 3, in the form of ahardenable fluid layer, by brushing, spraying or similar techniques.

FIG. 3 shows the finished foil 13 immediately after it has been removedfrom the die, illustrating its internally coated perforations 14 whichconverge toward the uncoated underside of substrate 3.

FIG. 4, in a similar cross-sectional view, shows the partial erosion ofthe exposed underside of the shearing foil by the co-operating blade orblades during its initial use. Thus, the undersurface of the substrate 3wears to a greater degree than its cutting edges 5, formed by the hardercoating 4, so that concavities 6 come into existence along this surface.The depth of these concavities has been indicated at at. As aconsequence of this phenomenon, the friction between the shearing foiland the cutter blade is reduced whereby the foil becomes less subject tostresses; at the same time its hard cutting edges 5 are effectivelysharpened to exhibit an acute angle a. The hard coating is also subjectto relatively little strain, e.g. upon a flexing of the foil, by virtueof the rounding of the outer edges 7 of the perforations 14 whichconverge toward the cutting edges 5.

While there has been described what is, at present, considered to be apreferred embodiment, it will be obvious to those skilled in the artthat various modifications may be made therein Without departing fromthe spirit and scope of my invention as defined in the appended claims.

I claim:

1. A shearing foil for a dry shaver having a movable cutter blade, saidfoil comprising a substrate body having perforations conforming to toothformation of said movable blade, said body having an inner surface forcontacting the movable blade and an outer surface, and a relatively thincoating of a material harder than'said substrate body on the outersurface of said substrate body and extending along the peripheries ofsaid perforations to the inner surface of said substrate bodyconfronting the movable blade, said inner surface being devoid of saidcoating so that said substrate body is substantially completely exposedthereat, thereby forming hard cutting edges along the rims of saidperforations at said inner surface.

2. A shearing foil as defined in claim 1 wherein at least said substratebody is metallic.

3. A shearing foil as defined in claim 2 wherein at least said substratebody includes nickel.

4. A shearing foil as defined in claim 1 wherein said perforationsconverge toward said inner surface and have rounded edges remote fromsaid inner surface.

5. A shearing foil as defined in claim 1 wherein said coating at theperiphery of said perforations forms an acute angle with said innersurface at the rims of said perforations.

6. A shearing foil as defined in claim 1 wherein said substrate body isof sufiicient softness to enable the formation of concavities in saidlower surface within the confines of said coatingby contact with themovable blade.

References Cited UNITED STATES PATENTS 3,064,349 11/1962 Futterer et a1.30-34651 X 3,169,317 2/1965 Futterer et a1. 30-34651 WILLIAM W. DYER,JR., Primary Examiner.

20 G. WEIDENFELD, Assistant Examiner.

